Conventionally, there has been known a wireless communication system in which devices communicate with each other by a short range wireless communication technique (e.g. see Japanese Laid-open Patent Publication No. 2009-77296).
In a Japanese wireless radio act, before a transmitter performing wireless communication begins the transmission of an electric wave, it is necessary to check whether a channel to be used is used for the transmission with another transmitter based on an intended use and a use frequency band. This is called a carrier sense. If the channel to be used is in use by the another transmitter, the transmitter cannot perform the transmission by using the channel, and the transmitter needs to perform the transmission after the another transmitter completes the transmission or to perform the transmission by using another channel. Here, also when the another channel is used, it is necessary to perform the carrier sense with the use of the another channel again before the transmission.